DUBBING PREVENTING DEVICE FOR VIDEO SIGNAL

• Main Author: YAMAMURA TAKAYA
• Format: Patent
• Language: English
• Published: 06.02.1992
• Subjects: ELECTRIC COMMUNICATION TECHNIQUE; ELECTRICITY; INFORMATION STORAGE; INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORDCARRIER AND TRANSDUCER; PHYSICS; PICTORIAL COMMUNICATION, e.g. TELEVISION

PURPOSE:To prevent illegal dubbing in an excellent way by inserting a signal generated sequentially into a video signal via a cryptographic circuit and comparing a signal obtained through the application of the generated signal to the cryptographic circuit with a succeeding inserted signal so as to discriminate the propriety of dubbing. CONSTITUTION:At first, a signal enabling dubbing is generated. An optional is sequentially generated from a cryptographic circuit 3 and fed to one fixed contact of a switch 6. Moreover, a switch 6 is changed over by a signal from a timing decoder 7 and a signal inserted with a signal generated sequentially by the cryptographic circuit 3 at a prescribed position of the video signal is generated. Then the signal is used to discriminate the propriety of dubbing. When the signal inserted at a prescribed position of the video signal is coincident with the signal generated from a cryptographic circuit 13 resulting from a preceding field signal sequentially, a signal detected by a coincidence detection circuit 15 is latched. On the other hand, they are dissident, the detection signal from the coincidence detection circuit 15 is not obtained and dubbing is inhibited.